"As this UV radiation penetrates to deeper areas, it knocks off oxygen atoms from molecules of silicon monoxide," says Wood. "These oxygen atoms are then free to combine with molecular hydrogen to form water molecules."

He says the ultra violet radiation must be coming from other stars. "IRC+10216 is so cool (around 2000°C) it's emitting most of its light in the infrared, and not producing any UV radiation."

According to Wood this discovery tells us more about the chemistry and the nature of the envelopes of these carbon rich stars as they reach the end of their lives.